Electric Shoes

So, here's my idea. I was thinking : mobile phone batteries are amazing. As the years pass, the batteries in the mobile phones that I buy last longer and longer and get smaller and smaller. The battery in my current phone - barely the size of a small book of matches - gives me a good week or so between charges, even with regular use.

I got to thinking - they're so small they could comfortably in the heel of a shoe. You could use them, perhaps, on cold mornings, or in wintery climates, to supply a nice burst of warmth, or a constant gentle warmth.

To add to the convenience of this idea, I imagined that perhaps you charge these batteries in much the same way as electric tooth brushes work (no visible socket/cables, simply resting the toothbruh in a cradle will charge it up). So perhaps you come home in the evening, take your shoes off... and just place them on a special mat in your closet, wardrobe, whatever.

Now : I think there might be one or two minor electrical current problems here. I know that heat is very energy intensive, and so perhaps there's insufficient charge in the battery to supply much heat. But perhaps there is enough for a gentle warmth for a period? Perhaps someone has an idea about the type of battery, keeping it small and light but strong enough to provide some constant gentle warmth? What about emerging battery technologies?

And I know the conducting mat might not be able to supply enough energy. My electric toothbrush seems to take about 2 days to charge up, and that ain't much energy.

Anyhoo, pull it off and no-one will ever suffer the discomfort of cold feet again. Jolly good :)